What exactly is the passive? What does it do to Latin words exactly? I read it in Lingua Latina Pars I Familia Romana on page 46 chapter VI. Here are some examples:Saccus portatur a servo.Sacci portantur a servis.

Passive means that the subject is receiving the action. For example, in your sentence "saccus portatur a servo", the saccus is being carried. In an active sentence, the direct object receives the action ("servus saccum portat"). Latin passive is equivalent to English "be ____ed" (e.g. "be killed" as opposed to "kill").